Alternator Not Charging

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Alternator Not Charging

swampedout
Hey folks,
Started driving the 250 and it's draining batteries. I found one small draw from the trailer brakes that the previous owner wired straight off the battery. I unplugged that for now but I went ahead and checked my voltage when the truck is running in the driveway and I had 2 batteries which tested around 12.6 when I first cranked the truck and minute by minute, they went down to 12.3 before I cut the engine off. Also did a voltage drop test across the negative post to alt. body, bracket, engine block and didn't see anything wrong.

Both of the batteries were recently charged off the vehicle.

I'm going to take the alternator in to bench test and hopefully it's just a bad unit. But because most of my problems don't seem to have simple solutions, what else can I test for? I'm not very familiar with the voltage regulator system here. Any tests I can run on it?

Thanks in advance.
Sam
1984 F250. 460. C6. 4x4.
 MSD Ignition. Airbag rear suspension
Whole buncha problems
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Re: Alternator Not Charging

swampedout






Here's a couple thousand more words better than I can describe this mess.
The alternator was hooked up so that the 4 wires soldered together into a red wire that connects at alternators battery position.
Then there is an orange wire that was going from one of the smaller terminals in the middle to the F connection on voltage regulator. No ground connection on alternator although there is a big negative cable on the top of the alternator bracket
Sam
1984 F250. 460. C6. 4x4.
 MSD Ignition. Airbag rear suspension
Whole buncha problems
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Re: Alternator Not Charging

85lebaront2
Administrator
In reply to this post by swampedout
Ok, first item, alternators, unless they are mounted in non-conducting bushings like my Chrysler, ground through the case to the mount bracket. The wires connected together, if it looks as though they are welded, that is a factory splice, it probably had friction tape on it or was potted in something originally (Detroit was changing a lot of wiring methods in the 80s and 90s.

That alternator looks like one of the 60 or 90 amp side terminal style know as a 1G for 1st generation which uses a remote (fender mounted) regulator rather then the integral regulator of the 2G and 3G designs. It is not a super difficult conversion to a 3G 130 amp unit from a Taurus 3.8L V6.

Does your truck have an ammeter? Full gauge package had that and was also built with a tachometer option.
Bill AKA "LOBO" Profile

"Getting old is inevitable, growing up is optional" Darth Vader 1986 F350 460 converted to MAF/SEFI, E4OD 12X3 1/2 rear brakes, traction loc 3:55 gear, 160 amp 3G alternator Wife's 2011 Flex Limited Daily Driver 2009 Flex Limited with factory tow package Project car 1986 Chrysler LeBaron convertible 2.2L Turbo II, modified A413

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Re: Alternator Not Charging

swampedout
Truck does have ammeter and tach. Ammeter seems to work. It sticks up at halfway mark.
A lot of the wiring is definitely not factory so it would be nice if that one splice is. Its the only soldering ive seen so far. PO seemed to use butt splices and crimp connects.
The red power wire will spark when it touches the alt case so I think I have power to it and a good circuit to negative.
So either alt is bad, regulator is bad or regulator wiring is bad?
Sam
1984 F250. 460. C6. 4x4.
 MSD Ignition. Airbag rear suspension
Whole buncha problems
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Re: Alternator Not Charging

ArdWrknTrk
Administrator
There is always the EVTM in the Resources folder for step by step diagnostics of the alternator and voltage regulator.
 Jim,
Lil'Red is a '87 F250 HD, 4.10's, 1356 4x4, Zf-5, 3G, PMGR, Saginaw PS, desmogged with a Holley 80508 and Performer intake.
Too much other stuff to mention.
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Re: Alternator Not Charging

swampedout
Thanks, I need to spend more time looking through the resources in this website. Sorry for not looking there first.
But luckily I think me and the old process of elimination might have solved the problem. Replaced the regulator and batteries were charging on idle. I let the truck run for a couple minutes and saw the batteries go up to 13+ so I'm happy for now. Glad I didn't have to get further into the wiring. The Gr stator wire goes from the regulator to the cab (and presumably ammeter?) and no stator wire is needed on the alternator itself. I still have a lot to learn.
Thanks for your help.
Sam
1984 F250. 460. C6. 4x4.
 MSD Ignition. Airbag rear suspension
Whole buncha problems
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Re: Alternator Not Charging

ArdWrknTrk
Administrator
This post was updated on .
I hate to say "look at the manual" but I was under a van changing calipers.  

There are two ways the 1G was wired.
If you had a light instead of a ammeter, the green/red wire would indeed excite the alternator.

Glad a simple regulator swap seems to have fixed your problem.  

Edit: The ammeter has red/orange wires.
I believe the green/red wire is key on power.
 Jim,
Lil'Red is a '87 F250 HD, 4.10's, 1356 4x4, Zf-5, 3G, PMGR, Saginaw PS, desmogged with a Holley 80508 and Performer intake.
Too much other stuff to mention.
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Re: Alternator Not Charging

Gsmblue
In reply to this post by swampedout
That 4 way splice looks like mine did. I pulled it apart and resoldered it.

Anyhow. Both my trucks had issues at the same time. One was a bad voltage regulator on the fender and the other was the alternator.

Once you bench test the alternator you will know!
1985.5 F-150 XL Explorer standard cab 5.0 EFI AOD 4x4
Daily Driver. We call her Eunice the Ute.

1982 Bronco XLT Lariat 351W AOD 4x4
Code name Esperanza, or Espy to her friends. Please see my Project thread for the blow by blow.

1984 F-350 XL Centurion crew cab 460 T19 4x4
"Eylza Dual-little"
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Re: Alternator Not Charging

Danny G
I had a similar problem, required a whole new wire run practically, new crimps, environmentals etc. I'm glad yours was a quick  fix but it looks like it wouldn't hurt to start thinking about redoing that wiring, or at least protecting the exposed stuff.
1986 F-150|Standard Cab|4x2|300Six|C6Transmission w/3.08 rear|Name:TBD
2021 Ranger XLT Super Crew
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Re: Alternator Not Charging

swampedout
Yea I knew when I bought this truck that the wiring was going to be a project. Im going through it bit by bit.
Sam
1984 F250. 460. C6. 4x4.
 MSD Ignition. Airbag rear suspension
Whole buncha problems